RNF4 interactome in heatshocked HeLa cells

ABSTRACT: Exposure of cells to heat or oxidative stress causes misfolding of proteins. To avoid toxic protein aggregation, cells have evolved nuclear and cytosolic protein quality control (PQC) systems. In response to proteotoxic stress cells also limit protein synthesis by triggering transient storage of mRNAs and RNA binding proteins (RBPs) in cytosolic stress granules (SGs). We demonstrate that the SUMO-targeted ubiquitin ligase (StUbL) pathway, which is part of the nuclear proteostasis network, regulates SG dynamics. We provide evidence that inactivation of SUMO deconjugases under proteotoxic stress initiates SUMO-primed, RNF4-dependent ubiquitylation of RBPs that typically condense into SGs. Impairment of SUMO-primed ubiquitylation drastically delays SG resolution upon stress release. Importantly, the StUbL system regulates compartmentalization of an amyotrophic lateral sclerosis (ALS)-associated mutant of FUS in SGs. We propose that the StUbL system functions as surveillance pathway for aggregation-prone RBPs in the nucleus thereby linking the nuclear and cytosolic axis of proteotoxic stress response. To better understand the role of RNF4 in the proteotoxic stress response we aimed to identify RNF4-associated protein complexes in cells exposed to heat stress. To allow immuno-affinity purification of endogenous RNF4 on anti-Flag agarose beads we used CRISPR/Cas9-mediated gene editing to integrate a C-terminal 3xFlag epitope tag into the genomic locus of RNF4 in HeLa cells. For the IP-MS experiment HeLa-RNF4-3xFlag cells or parental untagged control cells were exposed to heat stress for 1 h and RNF4-3xFlag together with associated proteins was captured on anti-Flag affinity beads. Tryptic peptides were analyzed by LC-MS/MS and data from three replicates were quantified by the Max Quant label-free quantification (LFQ) algorithm.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Cell Culture

DISEASE(S): Cervix Carcinoma

SUBMITTER: Jan Keiten-Schmitz  

LAB HEAD: Stefan Müller

PROVIDER: PXD017888 | Pride | 2023-06-30

REPOSITORIES: Pride